[cleanup] simplify Type_parser.function_param_with_id
[cleanup] simplify Type_parser.function_param_with_id

Summary: `function_param_with_id` has two callers, both of whom call `Parse.identifier` just before. moving that call into `function_param_with_id` avoids having to use `with_loc ~start_loc`.

Reviewed By: gkz

Differential Revision: D16429626

fbshipit-source-id: 5eaabe6a8532b52ae90a68e2eee857ef454d19f1

samwgoldman/flow,mroch/flow,samwgoldman/flow,facebook/flow,mroch/flow,mroch/flow,gabelevi/flow,facebook/flow,gabelevi/flow,samwgoldman/flow,gabelevi/flow,samwgoldman/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,gabelevi/flow,gabelevi/flow,facebook/flow,mroch/flow,samwgoldman/flow,mroch/flow,gabelevi/flow,facebook/flow,samwgoldman/flow,samwgoldman/flow,gabelevi/flow,facebook/flow